Cable system operators use Radio Frequency (RF) signals transmitted over coaxial cables to provide television and data services to customers. Normally these RF signals do not cause interference when in compliance with Federal Communication Commission (FCC) rules that limit interference. However, in some cases the RF signals can leak. Cable signal leaks occur when the RF signals transmitted within the cable system are not contained within the cable plant. Cable signal leaks may be caused by loose connectors, damaged cables, unshielded housings, or unterminated cables.
A cable plant uses many of the same frequencies to transmit programming as licensed to over-the-air broadcasters. Cable operators are considered by the FCC to be secondary users of these frequencies, so they are precluded from interfering with licensed users who are the primary users of these frequencies.
Cable signal leakage can interfere with the over-the-air services that are using the same frequencies as the cable plant near the vicinity of an RF leak. This can interfere with ham radio operators, cellular radio, emergency responders, and aircraft navigation systems. When interference from the cable plant occurs, it can hamper or endanger others.
The FCC has set maximum individual signal leakage levels for cable systems. The FCC is stricter with signal leakage levels for cable systems that interfere with aeronautical and/or navigation communications. Therefore, the FCC requires cable operators to have a periodic, on-going program to inspect, locate, and repair RF leaks in their cable plants. However, locating RF leaks in a cable plant can be difficult and time consuming, due to the complexity and size of a typical cable plant.
Cable system operator use Radio Frequency (RF) signals transmitted over coaxial cables to provide television and data services to customers. Normally these RF signals do not cause interference when the shielding integrity is good, but sometime damage occurs. Damage may be caused by corrosion, animal chews, craft error, or mechanical stress. When there is damage to cable shielding, cable signals may leak out causing interference with wireless services. Many of the RF frequencies used inside the coaxial cable are the same frequencies used for a variety of wireless communication services, such as aviation signals, Ham radio signals, broadcast signals and wireless LTE (long term evolution) 2-way communications. Additionally, when there is shield damage allowing signal egress, it may be accompanied by signal ingress, where cable services are negatively affected by wireless signals or electrical noise. The FCC has published leakage limits for field strength. One limitation with legacy leakage detection equipment is that when a distance between the leakage signal's source and a receiving antenna is not known, it is not possible to calculate if the field strength exceeds FCC limits at a test distance, which may be at 3 meters or 30 meters. Thus, there is a need to know measurement distance to calculate if a detected leak exceeds FCC limits.